The need to form a sterile, sealed connection between a pair of conduits arises particularly in the field of blood and blood component handling, as well as in other areas where a sterile connection between containers is desired.
In the blood handling field, it may be desired to make use of only one half of a unit of blood in a bag or the like. When this happens, it is customary to discard the nonused portion of the blood unit within a day after the access to the bag was made, even when efforts are made to maintain sterility by using conventionally accepted aseptic methods of access to the blood bag. This is so because only one or two air-borne bacteria could multiply in the stored blood to create the danger of septicemia, if the bacteria were allowed to multiply over a period of more than a very few hours, and the blood was then administered to a patient.
Accordingly, to eliminate the need for disposing of the remainder of a unit of blood when only a partial unit is needed, or for the many other reasons why sealed, sterile access between various containers would be desired, a considerable amount of research has taken place in developing aseptic fluid transfer systems. For example, Berkman, et al. U.S. Pat. No. 4,022,256, discloses a sterile connection means in which a heat-fusable tube carries an inner layer of plastic material which is nonmeltable at the temperature used. An allegedly-sterile connection is made by the use of a heating die pressing the nonmeltable layer through the melting outer layers of the tube, to provide a sterile connection between the two tubes, with the melted layers of the tube forming a single, perforated layer.
The invention of the Berkman patent requires a special heating die to press the nonmelting layer of material through the meltable layers of the conduits. Also, in the embodiment shown in the Berkman patent, the meltable material presses against the heating die. Any adhesion of the meltable material to the heating die when the die is pulled apart after the pressing step could cause the connection to rip open, or at least be seriously weakened.
In accordance with this invention, the use of a heating and pressing die for obtaining a sterile connection between two conduits is eliminated. Instead, radiant energy is used to selectively melt a portion of the conduit wall without providing any physical contact of a die or the like to the melting portion. Also, in this invention, mechanical connection means may be provided between the two conduits to protect the fused, sterile connection area from being mechanically ripped apart.